More contagious but also more dangerous? The California variant of the coronavirus, present in two forms called B.1.427 and B.1.429, is of concern to scientists.

Although it was discovered in December 2020 in California, this variant is still poorly understood. Two new American studies – which have not yet been published in scientific journals – nevertheless provide a clearer picture.

From 16 to 53% in two months

The first one of them was conducted at the University of California at San Francisco. She has been interested in the spread of the California variant and reports that in just two months, this strain has invaded an entire neighborhood of the city of San Francisco.

In fact, in November 2020, the California variant accounted for 16% of positive tests in the Mission District. This figure reached 53% between January 10 and 27, 2021, according to specialists. Their analyzes show that this variant is more contagious than the old strain, especially within the same outbreak.

40% more infectious

Results confirmed by the second study, conducted at the same university, which analyzed 2,172 virus samples collected from across California between September 2020 and January 2021.

No sign of this variant was present in the September samples, but by the end of January it had become the majority in the state, overtaking the old strain. Researchers estimate that cases caused by this variant are now doubling every 18 days.

And experiments carried out in vitro also show that B.1.427 / B.1.429 is 40% more infectious than the other variants.

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Twice as many viral particles

The study goes even further: analysis of samples taken from patients shows that the viral load, i.e. the number of copies of the virus in a given volume of fluid, such as nasal secretions or saliva for example, is higher with this variant.

Concretely, people infected with the new California variant produce twice as many viral particles as those infected with the other variants.

A more lethal variant?

But that’s not all: These researchers looked at the medical records of 308 cases of covid in San Francisco and found that the number of deaths was 11 times higher with the new variant than with the old strain.

Results to be confirmed on a larger number of patients, but which could suggest that the California strain is more lethal than the old one.

Possible re-infections

Finally, the researchers were interested in the body’s immune response to this variant. And the results obtained in vitro of concern: The antibodies of people who have previously had covid with the old variant do not seem to recognize the new variant and therefore do not block the infection.

If this observation is confirmed in vivo, this could mean that the California variant escapes the surveillance of the immune system and that it could cause re-infections, like the South African variant.

What about the effectiveness of vaccines against this variant? No data is currently available on this question.

In France since January?

While waiting to learn more about this variant, scientists already know that it has spread in 45 American states but also in Australia, Denmark, Mexico, Taiwan … and France, where six patients hospitalized in Alsace in February were carriers of this variant, depending on the daily Latest news from Alsace. Which would suggest that the Californian variant has been present in this department at least since January.

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